In numerous applications in a field of fluids, in particular for cooling heat engines, valves of this type are used for distributing a fluid entering various tracts as a function of characteristics, in particular temperature characteristics, of this entering fluid.
In a currently used valve, a free end of a piston of a thermostatic element is often rigidly connected to a check mechanism regulating flow of fluid into the valve, such that a distance of the valve from its seat is controlled by development of temperature of the fluid in which the thermostatic element is immersed.
Some operating conditions of heat engines may cause excessive pressure in water cooling circuits, whilst a thermostatic valve is not opened by thermal stresses as temperatures are too low. This excessive pressure may be harmful to some components of these circuits.
U.S. Pat. No. 5,482,010 and EP-A-0 694 681 propose thermo-pressostatic devices that are intended to prevent excessively high pressure on a side of a check mechanism that is remote from that on which the check mechanism is connected to a piston of a thermostatic regulation element. These devices are thus applied only to valves that have at least three fluid inlet ports and are equipped with two check mechanisms. Any differences in pressure within these valves, caused by simultaneous thermostatic control of the two check mechanisms, are then corrected by pressostatic regulation of one of the check mechanisms, a “by-pass check mechanism” or “short-circuit check mechanism”, which consists in pulling this check mechanism in an opposite direction to that controlled by expansion of wax of the thermostatic element. The valves described in the aforementioned documents do not, on the other hand, have any facilities for regulating an increase in pressure of fluid around the thermostatic element.
An object of the present invention is to propose a thermostatic valve that limits risks of damage in the event of pressure of fluid in the valve becoming excessively high, on a side of a regulating check mechanism on which this check mechanism is connected to a piston of a thermostatic element of the valve.